Chart



H. w. HILL.

CHART. APPLICATION FILED APR. 4, 131a.

Patented Aug. 31, 192%,

svroc AL s ank CHART j CURVE READ! G ADDITIONS ON 1 use 5 suns:

INVENTOR HARRY w. HILL.

ATTORNEYS STATES HARRY W. HILL, 0F SOUTHBRIDGE, IJIASSACHUSETTS, ASSIGNOB. T0 AMERICAN OPTICAL COMPANY, OF SOUTHBRIDGE, MASSACHUSETTS, A VOLUNTARY ASSOCIATION OF MASSACHUSETTS.

Specification of Letters Patent.

Application filed April 4, 1918. Serial No. 226,710.

To all whom it may concern:

Be'it known that I, HARRY "W. HI L, a citizen of the United States, residing at Southbridge, in the county of Worcester and State of Massachusetts, have invented certain new and useful Improvements in Charts, of which the following is a specification.

My invention relates to improvements in charts and has particular reference to a novel and improved construction and arrangement of chart particularly adapted for. use in the ordering of bifocal lenses.

The leading object of the present invention is the provision of a novel form of chart especially adapted for use in the ordering of semi-finishedbifocal lenses of that type in which the bifocal side of the lens has been finished, preferably to arbitrarily selected base curves, and in which the lens is intended to be sold in that form for subsequent finishing or completion.

A further object of my improvement is the provision of a chart which shall be so constructed and the several parts so arranged and combined that by the use of the chart a designating number for the particular blank is provided, which number will be composed in part at least of the actual power designations of the several portions of the bifocal lens, and will thusfacilitate the subsequent recognition of the lens as well as the initial determination of the blank through the use of my chart.

Other objects and advantages of my improved construction should be readily apparent by reference to the following specification taken in connection with the accompanying drawings, and it will be understood that I may make any variations in the specific features hereinafter described within the scope of the appended claims without departing from or exceeding the spirit of my invention, r

The figure represents a view of a chart constructed in accordance with and embodying the principles of my invention, semi-completed form, it being understood that the remainder of the chart as actually used will be in substantial accordance therewith. r

In the drawin I have illustrated my chart as, rectangn ar in. form, divided verti al'ly into a ser es columns, a y t one of a few but in lines 1, and horizontally into the severalrows of the columns, as by the lines 2, thus providing the series of squares or spaces 3 at the intersection of the rows and columns. At the top I have shown-an undivided space 4 bearlng a title,while at the top of the first column I have shown a space 5 bearing a'sui'table heading designating the elements contained in thatparticular column. At the top I have shown a heading space 6 bearing suitable wording to denote the purpose of the remaining columns and beneath this space the sub-heading spaces 7 bearing numerals or symbols 8 to denote the particular purpose Patented Au. 31, 1920.

of its special column, the several columns bearing beneath these sub headings com posite numbers or symbols 9, of which the column heading itself forms a part.

As previously mentioned, this chart is intended particularly to facilitate the-selection of semi-finished bifocal lens blanks, which blanks have been finished on the bifocal side to a predetermined curve, and the standard curves for the entire range of lenses being not over four or five different curves, the

first column on the chart is, therefore, preferably employed to list up these several base curves,'as' for example, 4:, 6, 8 and 10 being, as designated by the space-5, the curve on the disk side of the lens. The numerals 4, 6, 8 or 10 indicate that the curve in questionwould produce a dioptric power of that amount were the opposite face of the lens flat or plano. "Bifocal lenses, however,

are those in which there is a second or what is usually termed reading power, in the lens, which may be produced either by insetting a portion with an index of different refraction, or by forming a second and stronger curve on part of one face of the lens. In either event the result accomplished is that on what is known as the disk or bifocal side the lens will have an additional power ora power in excess of the power of the distance portion of the lens, irrespective of how the entire lens may be modified .by the application ofa curve to finish its opposite face.

These several powers or reading additions are also indicated in diopters, the indication on my chart showing the excess ofpower over the power of the curve of the distance portion'of the lens on the bifocal side.

- As denoted bythe words Reading addi- 't s in the W 9? p 95 ;,the numerals will be understood that I Order the blank in .50, 1.25 and 2.37 contained in the sub-heading spaces 7 indicate the dioptric values of the segment or reading portion of the lens if the segmentbearing face of the lens be finished to one of the curves, namely 4, 6, 8 and 10, specified in the first column. It

specifically mention this fact since, if the lens supposed to have 125 additional power in the bifocal or reading portion, when the bifocal face is ground off to a 4 curve, is ground ofl' instead to a 7 or 8 curve, for example, there will be a considerable difference in the excess of power created in the bifocal portion, so that the combination number found at the intersection of the two desired powers only designates a certain basic possibility for which the blank is primarily intended, with which knowledge before one the grinder can by suitable grinding on opposite faces of the blank produce several different relative powers in the final lens. The numbers .50,

1.25, 2.87 found in the horizontal row 7, re-

present the power of the reading portion of the blank; the numbers 4, 6, 8 and 10, the power of the distance portion; the number at the intersection of the rows and columns is a composite number formed of the distance and the reading powers, such as the number at the intersection of column 4 with row .50 is 4050, meaning the blank Will have a distance curve of 4 diopters and a reading power additional of .50 diopters. The zero between the 4 and 5 is in this instance a filler number because in some cases the reading power may have three figures, as in the next row where the power is 1.25, so three figures are reserved for the reading power and the power of the distance portion is placed before these three figures. Considering the original proposition, however, the following is an illustration of the use of my chart. I

F or example, the second column on the chart designates that the reading lenshas a power of fifty-hundredths, or one-half a diopter greater than the distance, while the fourth column designates that the reading lens has a power of two and thirty-seven hundredths greater than the distance. Taking these two for example in connection with the second row or 6 base curve, as regards the actual power of the bifocal portion, its value might be expressed in the first instance as a 6.50, while following it across the column four the lens there in question would in the bifocal part have a power of 8.37.

By the use of my improved chart, however, it is possible to have a designating number for the particular blank, which will enable the person desiring a certain lens to question, as for example a 6237 blank, and they will know from reference to my improved chart that the blank in question will have a 6 curve on the distance portion of the bifocal side and. the reading complishable through the improved arrangement of my chart, consisting in placing as a designation for either the columns or rows the numerals representing the curve on the distance portion of the disk side and placing as the designations of the other of the two in question, that is the columns or rows, a series ofdesignations indicating the addition in the bifocal portion of the lens, and then placing in each of the squares or spaces formed by the intersection of the rows and columns a composite number to be marked on and designate the blank, which number shall have certain predetermined portions, as for instance the last three places, containing in the chart as illustrated the designa tion of the columns, and the first place or places containing the designation of the rows, the two together forming the key number, as for example the number 6237 or the number 10125.

It will thus be seen that, broadly speaking, my chart consists of a series of intersecting columns and rows bearing suitable designations, and a series of numbers or symbols contained at the intersection of the several columns and rows and built up of a suitable consecutive arrangement of the headings or designations for the respective column and row.

I claim:

1. A chart for use in the selection of bifocal lens blanks, consisting of intersecting rows and columns, designations for one of said members indicating the power of the distance portion on the bifocal face, designations for the other indicating the excess of power in the reading portion over the power in the distance face, and a key num her at the intersection of the row and. column built up from the designations of the row and column, said key number comprising three sections, a two unit section denoting fractional diopter portions, a one unit section denoting whole diopter variations, and additional unit columns indicating the base on which the latter parts are figured.

2. A chart for use in the selection of semifinished bifocal blanks, having intersecting rows and columns, designations for one of said members expressing in diopters the curve on the distance portion of the bifocal face of the blank, designations for the other of said members indicating the excess of power in diopters of the bifocal portion over the distance portion, and a key number at semi-finished bifocal lens blanks ground to as a three unit predetermined base curves, including a series of rows and columns, one of said rows being designated Curve on disc side and the columns being collectively designated Reading additions, symbols in the Curve on disc side column indicating the several predetermined base curves, and sub headings under Reading additions indicating the additional power in the reading section for each particular column.

4. A chart for use in the selection of semifinished bifocal lens blanks ground to predetermined base curves, including a series of rows and columns, one of said rows being designated Curve on disc side and the columns being collectively designated Reading additions, symbols in the disc side column indicating the several predetermined base curves, sub headings under Reading additions indicating the additional power in the reading section for each particular column, and a blank number at the intersection of each of the rows and columns designating the particular blank which will possess the distance curve of the row and the addition of the column.

5. A chart, including intersecting rows and columns disposed as a double entry table, each of the of arguments, and the several points of the table columns bearing a lens blank designating symbol containing the respective arguments of the row and column written as an algebraic product, the argument of one'of said parts always being written in the "product symbol irrespective of the w designations a similar set for the columns, blank designating symbols being disposed at Curve on foregoing having its own set at the intersection of the rows and number of units in the argument of its respective line. r

6. A chart for the use in selection of semifinished bifocal lens blanks, comprising a I portion written in the form of a double'entry table, having rows and columns, suitable for the rows and columns 1ncluding a set of arguments for the rows and the intersection of the various rows and colthe several umns and including the argument of therespective row and respective'column written,

as an algebraic product. I v

7. A chart for use in the selection of semifinished' bifocal lens :blanks comprising a portion written in the form of a double entry table having rows and columns each provided with a set of arguments, the arguments of one being the actual distance portion dioptriccurve measures, and the arguments of the other being the actual excessofthe reading portion of the bifocal over the distance portion, and blank designating symbols disposed at the intersection of the 7 various rows and columns including the ar-e gument of the respective row and respective column wrltten as an algebraic productwhich by separation and addition will give the actual reading portion dioptric value.

In testimony'whereof I have aflixed my id signature, in presence of two witnesses.

v HARRY HILL.

Witnesses: p v

- H, K. PARsoNs, I V V ALICE G. HAsKELL, 

